This research, compares the observed seismogram of the PNG earthquake, C051099C with its synthetics in UGM, Wanagama, Indonesia, PMG, Port Moresby, PNG and CHTO, Chiang May, Thailand. The synthetic seismogram is calculated using preliminary earth model, which are the IASPEI91 and the anisotropic version of PREM. The seismogram comparison is conducted after imposing a low pass filter whose corner frequency is fixed at 20 mHz. We have found a real discrepancy on the travel time and waveform of some wave phases, namely P, S and Rayleigh and Love surface waves, by seismogram comparison in time domain. To correct the discrepancies, we need to adjust the earth structures, which include the depth of the Moho reflector, the velocity gradient of bh, and the propagation velocity of the P and S waves. The correction has been conducted in the earth layering system from the upper mantle down to the CMB, so that the excellent seismogram fitting was obtained for nearly all phases of the targeted waves. The used wave length for analysing is about 150 km. It turns out that the waveform of the body and surface waves is sensitive to the change of velocity structure. The analysis of repetitive ScS depth phases at closer distance stations gives better opportunity to investigate the S velocity structure near the CMB, something not used by other seismologists.